Merseyrail have been given a two-week deadline to provide ‘cast-iron’ assurances that guards will be retained on their service.
RMT made the announcement after travel bosses announced plans to introduce driver-only operated trains on the local rail network from 2020.
A January 26 deadline has been set by the transport union to both Merseytravel and Arriva Rail North, who operate Northern trains, for job security guarantees.
An estimated 220 jobs are set to be lost in Merseyrail’s radical overhaul despite a promise from the firm that there would be no compulsory redundancies.
But RMT’s general secretary Mick Cash has warned that they will enter into a formal dispute with Merseyrail if they cannot guarantee guard roles will not be axed.
He said: “The union’s position on Driver Only Operation is perfectly clear.
“We will not agree to any extensions of it, and will fight to retain the safety critical role of the guard and to keep a guard on the train.
“RMT has asked Merseyrail on numerous occasions for assurances that any new trains will have a second safety critical crew member on board and that the guard will be retained on all services.
“To date, the company has failed to provide the union with these assurances.
“If Scotrail, which is run by Abellio, the same franchisee that operates Merseyrail, can introduce new trains with guards, then so can Merseyrail.
“And if Stadler, which is building the Merseyrail trains, can build conventionally operated trains for the Greater Anglia franchise, which is also run by Abellio, then it can build them for Merseyrail.
“I have written to Merseyrail and informed them that if we haven’t received assurances over the safety critical role of the guard by January 26th then we will be in dispute with the company.”